<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>history对象2</title>
</head>
<body>
    <button id="left">上一个</button>
</body>
</html>
<script>
    var left = document.getElementById("left");
    left.onclick=function () {
        history.back();//上一个

    }
</script>